1. Field of the Invention
The invention relates to a controlled circuit, and more particularly to a circuit apparatus with General Purpose Input Output pin.
2. Description of the Related Art
As the pace of progress in technology, the peripherals of computer systems tend to become multiple. In these years, multi media facility, which is for capturing sound and vision, is the most popular one in computer peripherals. Therefore, every manufacturer would cudgel brains to devise the most attractive products for consumers in order to contend for possession of the market in such a competing market of multi media facilities. Let's take a scanner as an example. Since being effective is what modern people concern, an easily operated, handy and convenient scanner must be more welcome by consumers than one with complex operating schedules. There would be high market value to devise an easy-operated scanner with multi functions.
A highly competitive scanner must include a control processing unit with powerful functions to deal with complicated operating tasks. Nowadays, an Application Specific Integrated Circuit, ASIC, is used as a control processing unit to meet designs' requirements. On the practical applications, ASIC enables a scanner to proceed with a vision scan, a vision processing, enlargement, miniature, data input, data output and so on. That is why there are many pins and complex controls in ASIC. Among those pins, researchers can use General Purpose Input Output Pin, GPIO, as an entry of data delivery. For example, when a user presses a functional button of a scanner, the scanner can feed the input signal into ASIC through the pins of GPIO for further processing then the scanner can perform a reaction to the input signal. Likewise, for outputting data, a scanner can also use ASIC to output data through the pins of GPIO for further data processing.
Due to highly competition in the modern scanner market, every manufacturer would have to provide a scanner not only with basic scanning functions but also with additional multiple functions, which can play as competitive distinction and increase the possession ratio of the market. For example, in order to increase additional value of a scanner, a modem scanner can also provide multiple functions such as photo copy, fax, transmitting electric vision and so on. There is one thing needed to be aware of Although the additional functions of a scanner bring users a lot of convenience, in the hardware design of the scanner, it also need more GPIO pins in ASIC in order to meet the requirements of multiple functions. For instance, a scanner originally uses an ASIC with 100 pins. There are only 6 pins left for GPIO pins after deduction pins for necessary functions. Due to the increase of function buttons, a scanner needs more GPIO pins (like 10 pins). Therefore, a manufacturer has to use an ASIC with 104 pins. But, as the limitation of package techniques, the number of ASIC pins can not increase as many as needed. For example, the number can only be increased in 100, 125, and so on. Therefore, a manufacturer has to adopt an ASIC with 125 pins as the ASIC of a scanner. It would not only waste those not used pins, but also increase the cost of the product, and decrease the product usage of that product.